U.S. patent application number 12/689156 was filed with the patent office on 2010-10-07 for apparatus and method for interference minimization in body area networks using low duty cycle and preamble design.
This patent application is currently assigned to Samsung Electronics Co., Ltd.. Invention is credited to Kiran Bynam, Sridhar Rajagopal, Jianzhong Zhang.
Application Number | 20100255780 12/689156 |
Document ID | / |
Family ID | 42826597 |
Filed Date | 2010-10-07 |
United States Patent
Application |
20100255780 |
Kind Code |
A1 |
Rajagopal; Sridhar ; et
al. |
October 7, 2010 |
APPARATUS AND METHOD FOR INTERFERENCE MINIMIZATION IN BODY AREA
NETWORKS USING LOW DUTY CYCLE AND PREAMBLE DESIGN
Abstract
A device is adapted for use in a body area network capable of
low power communications wherein a number of piconets can operate
within close proximity. The device is configured to couple to a
plurality of secondary devices in a piconet. The device uses an
interference mitigation technique to enable the devices in the
piconet to use the same frequency and same time as a number of
adjacent piconets located in close proximity to the piconet. The
interference mitigation technique is at least one of a low duty
cycling operation; and a preamble sequence designed to operate
under interference
Inventors: |
Rajagopal; Sridhar; (Plano,
TX) ; Bynam; Kiran; (Bangalore, IN) ; Zhang;
Jianzhong; (Irving, TX) |
Correspondence
Address: |
DOCKET CLERK
P.O. DRAWER 800889
DALLAS
TX
75380
US
|
Assignee: |
Samsung Electronics Co.,
Ltd.
Suwon-si
KR
|
Family ID: |
42826597 |
Appl. No.: |
12/689156 |
Filed: |
January 18, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61212031 |
Apr 6, 2009 |
|
|
|
Current U.S.
Class: |
455/41.2 ;
455/63.1; 714/752; 714/E11.032 |
Current CPC
Class: |
H04W 84/18 20130101;
H04W 52/243 20130101; H04W 52/287 20130101; H04W 76/28
20180201 |
Class at
Publication: |
455/41.2 ;
714/752; 455/63.1; 714/E11.032 |
International
Class: |
H04B 7/00 20060101
H04B007/00; H03M 13/09 20060101 H03M013/09; G06F 11/10 20060101
G06F011/10 |
Claims
1. A device for use in a body area network capable of low power
communications, the device comprising: a controller configured to
couple to at least one secondary device, the device and at least
one secondary device coupled in a first piconet; and a transmitter
configured to communicate with the at least one secondary device
via a wireless communication channel, wherein the controller is
configured to perform an interference mitigation technique, the
interference mitigation technique comprising at least one of: a low
duty cycling operation; and at least one preamble sequence designed
to operate under interference.
2. The device as set forth in claim 1, wherein the wireless
communication channel is an ultra-wide band communication.
3. The device as set forth in claim 1, wherein the at least one
preamble sequence is configured to enable at least five piconets to
operate within a close proximity and using a same frequency
band.
4. The device as set forth in claim 1, wherein the preamble
sequence is based on one of a number of Kasami short sequences.
5. The device as set forth in claim 4, wherein the number of Kasami
short sequences comprises: a first sequence defined as: 1 1 1 1 1 1
0 1 0 1 0 1 1 0 0 1 1 0 1 1 1 0 1 1 0 1 0 0 1 0 0 1 1 1 0 0 0 1 0 1
1 1 1 0 0 1 0 1 0 0 0 1 1 0 0 0 0 1 0 0 0 0 0; a second sequence
defined as: 0 0 0 1 1 0 0 0 1 0 0 1 0 0 1 0 0 0 1 0 1 1 0 0 0 1 1 0
0 1 1 1 1 0 0 1 1 0 0 1 0 1 0 1 1 1 0 0 0 1 1 0 1 0 1 0 1 0 1 0 0 1
0; a third sequence defined as: 1 0 0 0 1 1 1 1 1 0 1 1 1 1 0 0 0 1
1 1 0 0 0 0 1 1 0 1 1 1 1 0 1 1 1 0 1 0 1 1 1 0 1 1 1 0 0 1 1 0 1 0
0 0 0 1 0 0 1 1 0 0 1; a fourth sequence defined as: 0 1 0 0 0 1 0
0 0 0 1 0 1 0 1 1 0 1 0 1 1 1 1 0 1 0 0 0 0 0 1 0 0 1 0 1 0 0 1 0 1
1 0 0 1 0 1 1 0 1 0 0 0 1 0 0 1 1 1 1 1 0 0; a fifth sequence
defined as: 1 0 1 0 0 0 0 1 1 1 1 0 0 0 0 0 1 1 0 0 1 0 0 1 1 0 .1
0 1 1 0 0 0 0 0 0 1 1 1 0 0 1 1 1 0 0 1 0 0 0 1 1 0 1 1 0 0 0 0 1 1
1 0; a sixth sequence defined as: 1 1 0 1 0 0 1 1 0 0 0 0 0 1 0 1 0
0 0 0 0 0 1 0 0 0 1 1 1 0 1 1 0 0 1 0 0 0 0 0 0 0 1 0 1 1 1 0 1 0 0
0 1 1 1 1 0 1 1 0 1 1 1; a seventh sequence defined as: 0 1 1 0 1 0
1 0 0 1 1 1 0 1 1 1 1 1 1 0 0 1 1 1 1 1 1 1 0 0 0 0 1 0 1 1 0 1 1 1
0 0 0 0 0 0 0 0 1 1 0 1 0 0 1 1 1 1 0 1 0 1 1; and an eighth
sequence defined as: 0 0 1 1 0 1 1 0 1 1 0 0 1 1 1 0 1 0 0 1 0 1 0
1 0 0 0 1 0 1 0 1 0 1 1 1 1 1 0 0 1 0 0 1 0 1 1 1 1 1 1 1 1 1 0 1 1
0 0 0 1 0 1.
6. The device as set forth in claim 1, wherein the low duty cycling
operation comprises at least one of: in a physical layer, on-off
keying within a symbol; and in a mac layer, on-off keying across
packets.
7. The device as set forth in claim 1, wherein the controller is
configured to: detect additional piconets during idle periods of
operation; inform a MAC layer regarding a number of detected
additional piconets; and adjust at least one of: its own low duty
cycle; and data rate.
8. The device as set forth in claim 7, wherein the controller is
configured to one of: lower the at least one of its own low duty
cycle and data rate when the number of additional piconets detected
has increased; and increase the at least one of its own low duty
cycle and data rate when the number of piconets detected has
decreased.
9. The device as set forth in claim 1, wherein the controller
further is configured to perform at least one of: adding a cyclic
redundancy check (CRC) code in a header of a communication from the
transmitter to the at least one secondary device, wherein the CRC
is masked with a preamble identifier; adding an offset value to a
scrambler seed code in the header; and explicitly signaling the
preamble identifier in the header.
10. An apparatus for use in a body area network comprising a
plurality of devices capable of low power communications, the
apparatus comprising: a processor configured to pair a first device
with least one secondary device, wherein the first device and at
least one secondary device are paired in a first piconet; and an
interface adapted to couple the processor to a transceiver
configured to communicate with the at least one secondary device
via a wireless communication channel, wherein the processor is
configured to perform an interference mitigation technique, and
wherein the interference mitigation technique comprises at least
one of: a duty cycling operation; and a preamble sequence designed
to operate under interference.
11. The apparatus as set forth in claim 10, wherein the wireless
communication channel is an ultra-wide band communication.
12. The apparatus as set forth in claim 10, wherein the at least
one preamble sequence is configured to enable at least five
piconets to operate within a close proximity and using a same
frequency band.
13. For use in a body area network capable of low power
communications, a method of operating a piconet, the method
comprising: communicating, by a central device, with at least one
paired device in the piconet; operating in close proximity with a
second device located in at least one adjacent piconet, the piconet
and the adjacent piconet sharing a same frequency and same time;
and performing an interference mitigation technique configured to
reduce a probability that communications in the adjacent piconet
will interfere with communications in the piconet, wherein the
interference mitigation technique comprises at least one of: a low
duty cycling operation; and a preamble sequence designed to operate
under interference.
14. The method as set forth in claim 13, wherein the at least one
preamble sequence is configured to enable at least five piconets to
operate within a close proximity and using a same frequency
band.
15. The method as set forth in claim 13, wherein the duty cycling
operation comprises at least one of: in a physical layer, on-off
keying within a symbol; and in a mac layer, on-off keying across
packets.
16. The method as set forth in claim 13, further comprising
detecting additional adjacent piconets during idle periods of
operation.
17. The method as set forth in claim 16, wherein detecting further
comprises changing a preamble search pattern to detect preambles
corresponding to the additional adjacent piconets.
18. The method as set forth in claim 16, further comprising, in
response to detecting at least one additional adjacent piconet,
adjusting at least one of: a low duty cycle operation and a data
rate.
19. The method as set forth in claim 18, wherein adjusting the at
least one of the low duty cycle operation and the data rate
comprises one of: lowering the at least one of the low duty cycle
and the data rate when a number of additional piconets detected
increases; and increasing the at least one of the low duty cycle
and the data rate when the number of additional piconets detected
has decreased.
20. The method as set forth in claim 13, further comprising
reducing, by the central device, an error recovery speed by at
least one of: adding a cyclic redundancy check (CRC) code in a
header of a communication from the transmitter to the at least one
secondary device, wherein the CRC is masked with a preamble
identifier; adding an offset value to a scrambler seed code in the
header; and explicitly signaling the preamble identifier in the
header.
Description
CROSS-REFERENCE TO RELATED APPLICATION(S) AND CLAIM OF PRIORITY
[0001] The present application is related to U.S. Provisional
Patent Application No. 61/212,031, filed Apr. 6, 2009, entitled
"PREAMBLE DESIGN FOR SIMULTANEOUSLY OPERATING PICONETS FOR
UWB-BASED BODY AREA NETWORKS". Provisional Patent Application No.
61/212,031 is assigned to the assignee of the present application
and is hereby incorporated by reference into the present
application as if fully set forth herein. The present application
hereby claims priority under 35 U.S.C. .sctn.119(e) to U.S.
Provisional Patent Application No. 61/212,031.
TECHNICAL FIELD OF THE INVENTION
[0002] The present application relates generally to body area
networks and, more specifically, to an apparatus, system and method
for substantially simultaneously operating piconets for UWB-based
Body Area Networks.
BACKGROUND OF THE INVENTION
[0003] A Body Area Network (BAN) is a short-range communication
network including multiple devices on or near a body. The
short-range communication network can include one or more devices
located up to three meters (3 m) apart. The devices can be located
on a human body. The devices serve a variety of applications such
as, for example, medical, personal fitness devices, consumer
electronics and personal entertainment.
SUMMARY OF THE INVENTION
[0004] A device for use in a body area network capable of low power
communications is provided. The device includes a controller
configured to couple to at least one secondary device. The device
and the secondary device are coupled together in a first piconet.
The device also includes a transmitter configured to communicate
with the secondary device via a wireless communication channel. The
controller is configured to perform an interference mitigation
technique. The interference mitigation technique can be either a
low duty cycling operation, at least one preamble sequence designed
to operate under interference, or both.
[0005] An apparatus for use in a body area network is provided. The
body area network includes a plurality of devices capable of low
power communications. The apparatus includes a processor configured
to pair a first device with at least one secondary device. The
first device and the secondary device are paired in a first
piconet. The apparatus is adapted to couple to a transceiver
configured to communicate with the secondary device via a wireless
communication channel. The processor is configured to perform an
interference mitigation technique. The interference mitigation
technique can be either a low duty cycling operation, at least one
preamble sequence designed to operate under interference, or
both.
[0006] A method of operating a piconet for use in a body area
network capable of low power communications is disclosed. The
method includes communicating, by a central device, with at least
one paired device in the piconet. The method also includes
operating in close proximity with a second device located in an
adjacent piconet when the piconet and the adjacent piconet share
the same frequency and same time. The method further includes
performing an interference mitigation technique configured to
reduce a probability that communications in the adjacent piconet
will interfere with communications in the piconet. The interference
mitigation technique can be either a low duty cycling operation, at
least one preamble sequence designed to operate under interference,
or both.
[0007] Before undertaking the DETAILED DESCRIPTION OF THE INVENTION
below, it may be advantageous to set forth definitions of certain
words and phrases used throughout this patent document: the terms
"include" and "comprise," as well as derivatives thereof, mean
inclusion without limitation; the term "or," is inclusive, meaning
and/or; the phrases "associated with" and "associated therewith,"
as well as derivatives thereof, may mean to include, be included
within, interconnect with, contain, be contained within, connect to
or with, couple to or with, be communicable with, cooperate with,
interleave, juxtapose, be proximate to, be bound to or with, have,
have a property of, or the like; and the term "controller" means
any device, system or part thereof that controls at least one
operation, such a device may be implemented in hardware, firmware
or software, or some combination of at least two of the same. It
should be noted that the functionality associated with any
particular controller may be centralized or distributed, whether
locally or remotely. Definitions for certain words and phrases are
provided throughout this patent document, those of ordinary skill
in the art should understand that in many, if not most instances,
such definitions apply to prior, as well as future uses of such
defined words and phrases.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] For a more complete understanding of the present disclosure
and its advantages, reference is now made to the following
description taken in conjunction with the accompanying drawings, in
which like reference numerals represent like parts:
[0009] FIG. 1 illustrates an example body area network according to
an exemplary embodiment of the disclosure;
[0010] FIG. 2A illustrates a central device according to
embodiments of the present disclosure;
[0011] FIG. 2B illustrates a secondary device according to
embodiments of the present disclosure;
[0012] FIG. 3 illustrates an Ultra Wide Band world-wide spectrum
according to an exemplary embodiment of the disclosure;
[0013] FIG. 4 illustrates two piconets operating in close proximity
according to embodiments of the present disclosure;
[0014] FIG. 5 illustrates a piconet distribution for a bandwidth
according to embodiments of the present disclosure;
[0015] FIG. 6 illustrates a multipath scenario of piconet
coexistence according to embodiments of the present disclosure;
[0016] FIG. 7 illustrates a low duty cycle in the PHY layer
according to embodiments of the present disclosure;
[0017] FIG. 8 illustrates a method for adjusting a low duty cycle
or data rate according to embodiments of the present
disclosure;
[0018] FIG. 9 illustrates a timing offset for coexistence of a
number of piconets operating within the same time and bandwidth
according to embodiments of the present disclosure;
[0019] FIG. 10A illustrates eight preamble codes based on a Kasami
code according to embodiments of the present disclosure;
[0020] FIG. 10B illustrates a packet structure according to
embodiments of the present disclosure; and
[0021] FIGS. 11A-11H illustrate auto-correlation and
cross-correlation for preamble sequences according to embodiments
of the present disclosure.
DETAILED DESCRIPTION OF THE INVENTION
[0022] FIGS. 1 through 11H, discussed below, and the various
embodiments used to describe the principles of the present
disclosure in this patent document are by way of illustration only
and should not be construed in any way to limit the scope of the
disclosure. Those skilled in the art will understand that the
principles of the present disclosure may be implemented in any
suitably arranged wireless communications network.
[0023] FIG. 1 illustrates an example body area network according to
an exemplary embodiment of the disclosure. The embodiment of the
BAN 100 shown in FIG. 1 is for illustration only. Other embodiments
could be used without departing from the scope of this
disclosure.
[0024] The BAN 100 includes a central device 105 and a number of
secondary devices 110-114. The secondary devices 110-114 are each
configured to couple, or "pair," with the central device 105. When
one or more secondary devices 110-114 pair with the central device
105, the central device 105 and paired secondary devices 110-114
form a piconet 120. The devices 105 and 110-114 in the piconet 120
can communicate with each other via a wireless communication. It
will be understood that illustration of five (5) secondary devices
in a piconet is for example purposes only and the piconet can
include any number of secondary devices without departing from the
scope of this disclosure.
[0025] The central device 105 can be configured to pair with one or
more compatible secondary devices 110-114 within a coverage area of
piconet 120, also referred to a cell. A dotted line shows the
approximate extents of coverage areas of the piconet 120, which are
shown as approximately elliptical for the purposes of illustration
and explanation only. It should be clearly understood that the
coverage area associated with the central device 105, for example,
coverage area of the piconet 120, may have other shapes, including
irregular shapes, depending upon the configuration of the central
device 105 and variations in the radio environment associated with
natural and man-made obstructions. The coverage area of the piconet
120 can vary in size based on the transmit power and the receive
power of the central device 105. For example, the central device
105 can be configured to pair with a number of secondary devices
110-114 located within a range from less than one (<1) meter to
five (5) meters. It will be understood that illustration of the
range from less than one (<1) meter to five (5) meters is for
example purposes only and other ranges could be used without
departing from the scope of this disclosure.
[0026] When paired, the central device 105 can send data to each of
the secondary devices 110-114. The central device 105 can send the
data individually, collectively, or to select groups of the
secondary devices 110-114. For example, central device 105 can send
data to secondary device D1 110 individually. Additionally, central
device 105 can send beacons to all secondary devices D1 110-114
substantially simultaneously to establish frame structure, provide
contention access period and do resource allocation.
[0027] Furthermore, when paired, the central device 105 can receive
data from each of the secondary devices 110-114. The central device
105 can receive the data individually from one of the secondary
devices 110-114 at time. For example, central device 105 can
receive data from secondary device D1 110 individually.
[0028] FIG. 2A illustrates a central device according to
embodiments of the present disclosure. The central device 105 shown
in FIG. 2A is for illustration only. Other embodiments could be
used without departing from the scope of this disclosure.
[0029] The central device 105 can be any type of electronic device
capable of controlling one or more secondary devices 110-114 when
paired with the secondary device 110-114. For example and not
limitation, the central device 105 can be a cellular phone,
Personal Data Assistant (PDA), a smart phone, portable computer,
media player (e.g., an MP3 player or the like), a headset, or a
media device (e.g., a video recorder or the like).
[0030] The central device 105 can include a microcontroller 205.
The microcontroller 205 can be a processor or processor array
configured to control the operations of the central device 105. In
some embodiments, the microcontroller 205 is configured to pair
central device 105 with one or more secondary devices 110-114.
[0031] The central device 105 also can include a transceiver 210
coupled to the microcontroller 205. In some embodiments, the
transceiver 210 can be a main transmission/reception device for
central device 105 and couples to the microcontroller 205 via an
interface (not illustrated) that is adapted to enable the
microcontroller 205 to use the transceiver 210. The transceiver 210
includes a transmit path (Tx) configured to transmit data signals
and messages to the secondary devices 110-114 via one or more
antenna 215. The transceiver 210 also includes a receive path (Rx)
configured to receive data signals and messages from the secondary
devices 110-114 via the antenna 215. In some embodiments, not
specifically illustrated, the central device 105 includes a
transmitter and a receiver as separate components.
[0032] The central device 105 also includes a memory 220. According
to some embodiments, microcontroller 205 is operable to store
information in the memory 220. Memory 220 can be any computer
readable medium, for example, the memory 220 can be any electronic,
magnetic, electromagnetic, optical, electro-optical,
electro-mechanical, and/or other physical device that can contain,
store, communicate, propagate, or transmit a computer program,
software, firmware, or data for use by the microprocessor or other
computer-related system or method. Memory 220 comprises a random
access memory (RAM) and another part of memory 220 comprises a
Flash memory, which acts as a read-only memory (ROM). In some such
embodiments, the microcontroller 205 is configured to execute a
plurality of instructions stored in a memory (not illustrated)
configured to cause the microcontroller 205 to perform a number of
operations of the central device 105.
[0033] In some embodiments, the central device 105 includes a User
Interface (UI) 225. The UI 225 is coupled to the microcontroller
205. The UI 225 is configured to receive one or more inputs from a
user in order to direct a function of the central device 105. For
example and not limitation, the UI 225 can be configured to place
the central device 105 in a pair mode such that the central device
105 commences a search operation for secondary devices 110-114 and
pairs with one or more of the secondary devices 110-114 located
within the coverage area 120. In some embodiments, the UI 225 can
be an Input/Output (I/O) port adapted to couple to an external
device, such as, for example, a personal computer, such that the
user can use the external device to direct operations or store
data, such as, for example, media data, in the central device
105.
[0034] FIG. 2B illustrates a secondary device according to
embodiments of the present disclosure. The secondary device 110
shown in FIG. 2B is for illustration only. Other embodiments could
be used without departing from the scope of this disclosure.
[0035] The secondary device 110 can be any type of electronic
device capable of pairing with the central device 105. For example
and not limitation, the secondary device 105 can be a health
monitor device, a sensor, an access point, a remote control, a
personal storage device, a video display device, a remote
beam-finder, a global positioning system device, a cellular phone,
Personal Data Assistant (PDA), a smart phone, portable computer,
media player (e.g., an MP3 player or the like), a headset, an
automobile, or a media device (e.g., a video recorder or the
like).
[0036] The secondary device 110 can include a microcontroller 255.
In some embodiments, the microcontroller 255 can be a processor or
processor array configured to control the operations of the
secondary device 110. In some embodiments, the microcontroller 255
is configured to pair secondary device 110 with the central device
105.
[0037] The secondary device 110 also can include a transceiver 260
coupled to the microcontroller 255. In some embodiments, the
transceiver 260 can be a main transmission/reception device for
secondary device 110 and couples to the microcontroller 255 via an
interface (not illustrated) that is adapted to enable the
microcontroller 255 to use the transceiver 260. The transceiver 210
includes a transmit path (Tx) configured to transmit data signals
and messages to the central device 105 via one or more antenna 265.
The transceiver 260 also includes a receive path (Rx) configured to
receive data signals and messages from the central device 105 via
the antenna 265. In some embodiments, not specifically illustrated,
the secondary device 110 includes a transmitter and a receiver as
separate components.
[0038] The secondary device 110 also includes a memory 270.
According to some embodiments, microcontroller 255 is operable to
store information in the memory 270. Memory 270 can be any computer
readable medium, for example, the memory 270 can be any electronic,
magnetic, electromagnetic, optical, electro-optical,
electro-mechanical, and/or other physical device that can contain,
store, communicate, propagate, or transmit a computer program,
software, firmware, or data for use by the microprocessor or other
computer-related system or method. Memory 270 comprises a random
access memory (RAM) and another part of memory 270 comprises a
Flash memory, which acts as a read-only memory (ROM). In some such
embodiments, the microcontroller 255 is configured to execute a
plurality of instructions stored in a memory (not illustrated)
configured to cause the microcontroller 255 to perform a number of
operations of the secondary device 110.
[0039] In some embodiments, the microcontroller 255 is
preconfigured to cause the secondary device 110 to pair with a
central device 105. The secondary device 110 can pair with the
central device 105 in response to a pairing signal received from
the central device 105. In some embodiments, the secondary device
110 is configured to actively search and pair with the central
device 105.
[0040] In some embodiments, the secondary device 110 includes a
user interface (not illustrated). The user interface can be coupled
to the microcontroller 255. The UI 255 is configured to receive one
or more inputs from a user in order to direct a function of the
secondary device 110. For example and not limitation, the user
interface can be configured to place the secondary device 110 in a
pair mode such that the secondary device 110 commences a search
operation for central device 105. In some embodiments, the user
interface can be an Input/Output (I/O) port adapted to couple to an
external device, such as, for example, a personal computer, such
that the user can use the external device to direct operations or
store data, such as, for example, media data, in the secondary
device 110.
[0041] The microcontroller 255 can be configured to be responsive
to commands received from the central device 105. For example, the
secondary device 110 can receive commands via antenna 265 and
transceiver 260. The microcontroller 255 can interpret the commands
and alter one or more functions of the secondary device 110 in
response to the commands. As an additional example, the
microcontroller 255 can direct a playback of a media file stored in
memory 270 through a speaker (not illustrated) in the secondary
device 110. As a further example, the microcontroller 255 can
direct the transmission of data, such as, for example, stored in
memory 270 or sensed via sensor (not illustrated), to the central
device 105.
[0042] FIG. 3 illustrates an Ultra Wide Band world-wide spectrum
according to an exemplary embodiment of the disclosure. The
embodiment of the Ultra Wide Band (UWB) world-wide spectrum shown
in FIG. 3 is for illustration only. Other embodiments could be used
without departing from the scope of this disclosure.
[0043] IEEE 802.15.6, the contents of which are incorporated by
reference in their entirety, is developing a standard for BAN and
has proposed a co-existence requirement of at least 10 piconets to
co-exist. UWB is very interesting for BAN due to the unlicensed
band, low transmit power, and ability to work under interference
due to large bandwidth. UWB, however, is unable to support more
than two bands globally due to the 500 MHz requirement.
Accordingly, when using UWB, at least ten piconets need to operate
within two frequency bands, which implies that at least five
piconets may need to operate in the same band at the same time.
[0044] The BAN is configured for a broad range of possible devices,
both central devices 105 and secondary devices 110-114. The BAN can
be configured to utilize a low power environment for operation on,
in and around the human body. It will be understood that BAN
operation is not limited to operation on, in and around the human
body, but can be applicable to other bodies, such as, for example,
animals, and man-made objects. The BAN also is configured for a
broad range of media types and a variety of applications including
medical, consumer electronics and personal entertainment. In some
embodiments, therefore, the central device 105 and secondary
devices 110-114 can be configured to use UWB.
[0045] In some embodiments, at least ten (10) piconets can operate
within a 6.times.6.times.6 meter area. For example, in some
embodiments, at least sixteen (16) piconets can operate within a
6.times.6.times.6 meter area. Additionally, the piconets can be
configured to operate globally.
[0046] The UWB spectrum, however, is restricted for use in some
countries. For example, the United States UWB spectrum 305
comprises a range from 3.1 GHz to 10.6 GHz. The Japanese UWB
spectrum 310 comprises a range from 7.25 GHz to 10.25 GHz. The
Korean UWB spectrum 315 comprises a range from 7.2 GHz to 10.2 GHz.
The European UWB spectrum 320 comprises a range from 6 GHz to 8.5
GHz. Accordingly, a common globally available UWB spectrum 325 is
approximately 1.25 GHz wide (e.g., a maximum of 8.5 GHz in the
European UWB spectrum 320--the minimum of 7.25 GHz in the Japanese
UWB spectrum 310).
[0047] In some embodiments, each piconet operates within a
bandwidth of five hundred Megahertz (500 MHz). Therefore, the ten
or more piconets are configured to operate within two (2) frequency
bands of 500 MHz each. As such, the piconets may have overlapping
resources in time and frequency and may cause interference in
operation. Since each piconet can operate independently of other
piconets within an area, coordination of time or frequency
resources between piconets can be challenging.
[0048] FIG. 4 illustrates two piconets operating in close proximity
according to embodiments of the present disclosure. The piconets
shown in FIG. 4 are for illustration only. Other embodiments could
be used without departing from the scope of this disclosure.
[0049] In the example illustrated in FIG. 4, Piconets P1 405 and P2
410 are operating in close proximity to each other. For example, P1
405 and P2 410 can be located within a 6.times.6.times.6 meter
area. P1 405 includes a central device 105a and a number of
secondary devices 110a-114a. P2 410 includes a central device 105b
and a number of secondary devices 110b-114b.
[0050] Secondary device 111b is paired with central device 105b. As
such, secondary device is located in and communicates in P2 410.
Secondary device 111b can be, for example, an MP3 player and
central device 105b can be, for example, a smart phone. Secondary
device 111b is located such that secondary device 111b also is
within a coverage area of P1 405. Therefore, secondary device 111b
can receive (e.g., "hear") signals from central device 105a. When
P1 405 and P2 410 share the same frequency band and same time, the
signals that secondary device 111b receives from central device
105a can be interference signals. That is, secondary device 111b
can experience inter-piconet interference.
[0051] FIG. 5 illustrates a piconet distribution for a bandwidth
according to embodiments of the present disclosure. The embodiment
of the piconet distribution 500 shown in FIG. 5 is for illustration
only. Other embodiments of the piconet distribution 500 could be
used without departing from the scope of this disclosure.
[0052] In some embodiments, five (5) piconets can operate within
the same operating band at the same time. For example, P1 through
P5 can operate at the same time in a first bandwidth 505 while P6
through P10 can operate at the same time in a second bandwidth 510.
Therefore, receivers in the secondary devices 110-114 for each
respective piconet (P1-P5 for the first bandwidth 505 and P6-P10
for the second bandwidth 510) can receive transmissions from other
piconets at the same time. Therefore, the piconets can be
configured to operate at the same time and within the respective
bandwidth 505, 510 by using interference mitigation techniques that
can include one of a low duty cycle, a modified preamble designed
to operate under interference, and an error recovery mechanism in
order to reduce interference resulting from the signals from other
piconets operating at the same time within the same frequency
bandwidth.
[0053] Two processes exist for attaining low duty cycle for BAN.
The first process is at the MAC layer (macro) whereby spacing
between transmissions is increases. The second process is at the
Physical (PRY) layer (micro) whereby pulse-based transmission is
used such that only a part of the symbol contains transmission.
[0054] FIG. 6 illustrates piconet coexistence according to
embodiments of the present disclosure. The embodiment of the
piconet coexistence 600 shown in FIG. 6 is for illustration only.
Other embodiments could be used without departing from the scope of
this disclosure.
[0055] A receiver 605 is paired with transmitter 610 such that the
receiver 605 and transmitter 610 are part of a piconet (such as,
for example, piconet P1 410 shown in FIG. 4). For example, receiver
605 can be located in secondary device 111b and transmitter can be
located in central device 105b. It will be understood that
illustration of the receiver 605 located in the secondary device
111b and the transmitter 610 located in the central device 105b is
for example purpose only and embodiments wherein the receiver 605
is located in a central device and/or the transmitter 610 is
located in a secondary device could be used without departing from
the scope of this disclosure.
[0056] The receiver 605 receives communications from the
transmitter 610 via a first channel (h1) 615. The receiver 605 also
can hear (e.g., receives) communications from transmitters 620b-e
located in other piconets (P2-P5). For example, a transmitter (TX2)
620b, located in piconet (P2) sends transmissions along a second
channel (h2) 625b. Additionally another transmitter (TX5) 620e
located in piconet (P5) sends transmissions along a fifth channel
(h5) 625e. In the example illustrated in FIG. 6, additional
interfering transmitters (e.g., transmitters 620c-d) located in
additional proximate piconets (P3-P4 and associated channels
625c-d) communicating along respective channels are not illustrated
for clarity purposes but are represented by ellipsis (". . . ").
The receiver 605 also hears Additive White Gaussian Noise (AWGN),
as represented by the AWGN channel 630. Depending upon the
distances, the information received by the receiver 605 can include
communications from the transmitter 610 and signals from channels
h2 625b through h5 625e and AWGN 630. Therefore, the receiver
experiences interference from h2 625b through 625e and AWGN 630.
Accordingly, in some embodiments, the transmitter 610 and receiver
605 in each piconet are configured to perform interference
mitigation by utilizing one or more of a low duty cycle, a modified
preamble design, and an error recovery mechanism.
[0057] FIG. 7 illustrates a low duty cycle in the PHY layer
according to embodiments of the present disclosure. The embodiment
of the duty cycle 700 shown in FIG. 7 is for illustration only and
could be extended to the MAC layer duty cycling as well. Other
embodiments could be used without departing from the scope of this
disclosure.
[0058] In some embodiments, each piconet can be configured to
utilize a duty cycle. For example, each of the devices in P1 405
can be configured to utilize duty cycling with modulation such as,
for example, a phase shift keying or an On-Off Keying (OOK)
modulation technique in order to meet low power requirements for
BAN. Using OOK, for example, the central device 105 can power down
(e.g., sleep) the transmitter, and, optionally, additional
electronic components, during OFF-periods of time. During
ON-periods, the central device 105 can power-up the transmitter
and, optionally, additional electronic components that were powered
down. The OOK can be performed within symbols within the PHY layer
and across packets in the mac layer. In some embodiments, the
central device 105 instructs the secondary devices 110-114 to
perform OOK in coordination with the central device 105.
[0059] Using duty cycling, an increased resistance to interference
from multiple piconets can be provided. For example, P1 can use a
four percent (4%) duty cycle for the ON-period. The 4% duty cycle
can roughly equate to a point sixty-four percentage (0.64%)
probability that P1 will experience interference from the four
additional piconets (P2-P5).
[0060] In FIG. 7, the spikes 705 represent an ON-time used by a
first piconet (such as, for example, P1 405) to send data when P1
405 uses a 4% duty cycle within symbols in the PHY layer for
transmission with pulse modulation using OOK. Therefore, each of
the piconets, P1-P5, can use, for example, a 4% duty cycle for
transmission with pulse modulation using OOK. Accordingly, if P1-P5
are uncoordinated and include random offsets with respect to each
other, the probability for interference between two or more of the
piconets, P1-P5, can be relatively small.
[0061] FIG. 8 illustrates a method for adjusting a low duty cycle
or data rate according to embodiments of the present disclosure.
The process 800 shown in FIG. 8 is for illustration only. Other
embodiments could be used without departing from the scope of this
disclosure.
[0062] In some embodiments, the low duty cycle and data rates can
be varied (such as, adjusted) based on observed interference. For
example, to determine if significant interference from nearby
piconets exists, P1 405 can be configured to detect one or more
nearby piconets, such as, for example, P2-P5. In block 805, P1 405
performs a search for preamble search patterns for piconets located
in proximity to P1 405. P1 405 can perform the search during idle
time periods or during piconet formation. If P1 405 detects one or
more preamble search patterns corresponding to one or more of
P2-P5, P1 405 can provide interference information to the MAC layer
in block 810. The interference information can include a number of
interfering piconets with corresponding preamble search patterns.
In response to receiving the interference information, in block
815, the MAC layer can adjust the low duty cycle, the data rate, or
both, for P1 405 to better enable operation of P1 405 to coexist
with the detected piconets in proximity to P1 405.
[0063] FIG. 9 illustrates a timing offset for coexistence of a
number of piconets operating within the same time and bandwidth
according to embodiments of the present disclosure. The embodiment
of the timing offset 900 shown in FIG. 9 is for illustration only.
Other embodiments could be used without departing from the scope of
this disclosure.
[0064] In some embodiments, the piconets (P1-P5) each utilize an
interference mitigation preamble design. The preamble included in
the beginning of a data transmission. The preamble helps
synchronize to the correct network. The preamble design illustrates
five (5) sequences configured to enable the piconets (P1-P5) to
operate within a frequency band (such as, for example, bandwidth
505 in FIG. 5) without causing interference between the piconets.
The preamble design, however, includes eight (8) sequences.
[0065] Further, the sequences for the preamble design can include
the following properties: Auto-correlation and Cross-correlation.
Auto-correlation is the ability by a receiver in a piconet (for
example, receiver 605 in P1 405) to distinguish a signal from the
transmitter 610 in P1 405 with time-shifted versions of the signal
from the transmitter 610 in P1 405. That is, the preamble sequence
is configured to enable the receiver 605 in P1 405 to be able to
find its own piconet sequence in presence of noise and multipath
effects. Cross-correlation is the ability of the receiver 605 in P1
405 to distinguish a signal from the transmitter 610 in P1 405 from
set of time-shifted versions of other signals (e.g., from one or
more of P2-P5) in a set. That is, the preamble sequence further is
configured to enable the receiver 605 in P1 405 to find its own
sequence in presence of other sequences, noise and multipath
effects.
[0066] The preamble design, in general, can be based on any one of:
Walsh Codes, Gold codes and Kasami codes for binary sequences; and
Zadoff-Chu codes and Generalized Chirp Like codes for complex
sequences. For example, the preamble design can be based on a
Kasami code. However, for BAN, it is important to design codes that
work under non-synchronized conditions and have good auto-
and--cross-correlation properties within the code set. Since BAN
also is intended to be low power, BAN supports non-coherent
receivers where only the energy of the signal is received.
Therefore, it is not possible to use complex sequences such as
Zadoff-Chu for BAN.
[0067] Based on the constraints for preamble design for BAN, such
as: (a) requirement for at least ten piconets co-existing; (b)
availability of two frequency bands, implying at least five (5)
piconets per band; (c) choice of using non-coherent receivers; and
(d) a need to have good auto-correlation and cross-correlation
properties, some embodiments utilize Kasami sequences. Kasami
sequences have optimal cross-correlation values touching the Welch
lower bound, and are good for asynchronous communication. The
Kasami short set sequences were selected and searched based on the
preamble design constraints for BAN to obtain the following eight
sequences:
[0068] Sequence 1: 1 1 1 1 1 1 0 1 0 1 0 1 1 0 0 1 1 0 1 1 1 0 1 1
0 1 0 0 1 0 0 1 1 1 0 0 0 1 0 1 1 1 1 0 0 1 0 1 0 0 0 1 1 0 0 0 0 1
0 0 0 0 0
[0069] Sequence 2: 0 0 0 1 1 0 0 0 1 0 0 1 0 0 1 0 0 0 1 0 1 1 0 0
0 1 1 0 0 1 1 1 1 0 0 1 1 0 0 1 0 1 0 1 1 1 0 0 0 1 1 0 1 0 1 0 1 0
1 0 0 1 0
[0070] Sequence 3: 1 0 0 0 1 1 1 1 1 0 1 1 1 1 0 0 0 1 1 1 0 0 0 0
1 1 0 1 1 1 1 0 1 1 1 0 1 0 1 1 1 0 1 1 1 0 0 1 1 0 1 0 0 0 0 1 0 0
1 1 0 0 1
[0071] Sequence 4: 0 1 0 0 0 1 0 0 0 0 1 0 1 0 1 1 0 1 0 1 1 1 1 0
1 0 0 0 0 0 1 0 0 1 0 1 0 0 1 0 1 1 0 0 1 0 1 1 0 1 0 0 0 1 0 0 1 1
1 1 1 0 0
[0072] Sequence 5: 1 0 1 0 0 0 0 1 1 1 1 0 0 0 0 0 1 1 0 0 1 0 0 1
1 0 1 0 1 1 0 0 0 0 0 0 1 1 1 0 0 1 1 1 0 0 1 0 0 0 1 1 0 1 1 0 0 0
0 1 1 1 0
[0073] Sequence 6: 1 1 0 1 0 0 1 1 0 0 0 0 0 1 0 1 0 0 0 0 0 0 1 0
0 0 1 1 1 0 1 1 0 0 1 0 0 0 0 0 0 0 1 0 1 1 1 0 1 0 0 0 1 1 1 1 0 1
1 0 1 1 1
[0074] Sequence 7: 0 1 1 0 1 0 1 0 0 1 1 1 0 1 1 1 1 1 1 0 0 1 1 1
1 1 1 1 0 0 0 0 1 0 1 1 0 1 1 1 0 0 0 0 0 0 0 0 1 1 0 1 0 0 1 1 1 1
0 1 0 1 1
[0075] Sequence 8: 0 0 1 1 0 1 1 0 1 1 0 0 1 1 1 0 1 0 0 1 0 1 0 1
0 0 0 1 0 1 0 1 0 1 1 1 1 1 0 0 1 0 0 1 0 1 1 1 1 1 1 1 1 1 0 1 1 0
0 0 1 0 1
[0076] These eight (8) sequences can be used for preamble
co-existence, for example, for IEEE 802.15.6 BAN
standardization.
[0077] FIG. 10A illustrates a packet structure according to
embodiments of the present disclosure. The embodiment of the packet
structure 1005 shown in FIG. 10A is for illustration only. Other
embodiments could be used without departing from the scope of this
disclosure.
[0078] The packet structure 1005 is configured for low duty cycle
interference mitigation and piconet coexistence. The packet
structure 1005 includes a preamble 1010, a header 1015 and a
payload 1020. The preamble 1010 can be one of eight 63-bit Kasami
sequences for piconet co-existence such as OOK and can be repeated
multiple times.
[0079] FIG. 10B illustrates eight preamble codes based on a Kasami
code according to embodiments of the present disclosure. The
embodiment of the preamble codes 1030 shown in FIG. 10B is for
illustration only. For example, the `0` and `1` pattern can be
interchanged. Additionally, a `-1` and `1` can be used in place of
`0` and `1` for coherent detection, and BPSK modulation. Further,
other embodiments could be used without departing from the scope of
this disclosure.
[0080] The example shown in FIG. 10B illustrates the specified
eight (8) preamble sequences that include high auto-correlation and
low cross-correlation. The specified codes, based on the Kasami
small set family, include a length of sixty-three (63). FIGS.
11A-11H illustrate the auto-correlation and cross-correlation for
each of the codes shown in the example illustrated in FIG. 10B.
[0081] In the legend, the first number shows the interfering
piconet and the second number shows the desired piconet. For
example, in FIG. 11A, the bottom number in the legend is `81`. This
number (`81`) corresponds to interfering piconet `8` (e.g., signal
from P8) and desired piconet `1` (e.g., signal from P1). If the
interfering piconet and desired piconet are the same, the plot
shows the auto-correlation. Alternatively, if the interfering
piconet and desired piconet are not the same, the plot shows the
cross-correlation between the codes. For example, signal spike 1105
corresponds to auto-correlation of P1 (e.g., P1's ability to
distinguish P1's own signal from a time-shifted versions of its own
signal). Further, signal spike 1110 corresponds to auto-correlation
of P2 (e.g., P2's ability to distinguish P2's own signal from a
time-shifted versions of its own signal); signal spike 1115
corresponds to auto-correlation of P3 (e.g., P3's ability to
distinguish P3's own signal from a time-shifted versions of its own
signal); signal spike 1120 corresponds to auto-correlation of P4
(e.g., P4's ability to distinguish P4's own signal from a
time-shifted versions of its own signal); signal spike 1125
corresponds to auto-correlation of P5 (e.g., P5's ability to
distinguish P5's own signal from a time-shifted versions of its own
signal); signal spike 1130 corresponds to auto-correlation of P6
(e.g., P6's ability to distinguish P6's own signal from a
time-shifted versions of its own signal); signal spike 1135
corresponds to auto-correlation of P7 (e.g., P7's ability to
distinguish P7's own signal from a time-shifted versions of its own
signal); and signal spike 1140 corresponds to auto-correlation of
P8 (e.g., P8's ability to distinguish P8's own signal from a
time-shifted versions of its own signal). As can be seen from the
figures, the specified preamble patterns include excellent
cross-correlation properties, enabling asynchronous operation
between the piconets.
[0082] Furthermore, the preamble design with eight (8) sequences is
configured for use in one frequency band, such as, for example,
frequency bandwidth 505 in FIG. 5. Therefore, these codes could be
repeated for the other frequency band (e.g., frequency bandwidth
510 in FIG. 5), thus providing up to sixteen (16) simultaneously
operating piconets (P1-P8 and P9-P16) for BAN, while maintaining
low power requirements. In some embodiments, in order to help with
adjacent channel rejection, and adjacent band ID could also be
added into the preamble ID, thereby providing 16 unique preamble
IDs.
[0083] In some embodiments, the devices in P1 405 are configured to
perform a combination of interference mitigation techniques. In
some such embodiments, although duty cycling operations and
preamble sequence can minimize the chance of interference and
misdetection of the desired piconet preamble, P1 405 performs
additional steps in order to recover from an error in preamble
detection. For example, in case of strong interference or if the
preamble length, or the number of preamble repetitions, is
shortened to save power, P1 405 can be configured to perform one or
more of: [0084] 1) a masking operation: the masking operation can
include applying an 8-bit CRC that can be added for the header for
the communication and masked with the preamble ID, wherein a
frequency band choice can be included as part of the header; and
[0085] 2) an offset operation: an additional offset can be added to
a scrambler seed code in the header and this offset can be linked
to the preamble ID; and [0086] 3) explicitly signaling the preamble
ID in the header. However, the receiver may need to decode the
header completely in order to know whether the preamble is for the
desired piconet.
[0087] Although the present disclosure has been described with an
exemplary embodiment, various changes and modifications may be
suggested to one skilled in the art. It is intended that the
present disclosure encompass such changes and modifications as fall
within the scope of the appended claims.
* * * * *